The effect of periapical rarefying osteitis on cortical and cancellous bone. A study comparing conventional radiographs with computed tomography

Objective: To determine whether erosion of the cortical plate is necessary for successful radiographic identification of periapical rarefying osteitis . Methods: Forty-two periapical osteitic lesions were diagnosed from periapic al radiographs of 26 patients who were subsequently examined by cross-secti onal computed tomography (CT), The relation of the lesions to the buccal an d lingual cortical plates was determined and their size measured. Results: The 42 lesions varied in size from 2-10 mm. Thirty one (74%) lesio ns diagnosed on the periapical radiographs were limited on CT to the cancel lous bone with no erosion of the cortical plates. The 11 lesions with corti cal erosion were randomly located throughout the jaws. Erosion was due to e ither the eccentric buccal or lingual location of the tooth apex, large siz e (>6 mm) of the lesion or narrowness of the jaw. Conclusions: Periapical lesions can be diagnosed from periapical radiograph s while they are limited to the cancellous bone and before they have eroded the cortices.